An O-Week activity designed to provide students with inspiration has taken a sinister turn, leading to a student opening disturbing hand-written letters that were mailed to her home.

Malaysian exchange student Ashleigh Thia received two official Monash University envelopes last Thursday, but when she opened them she was shocked to discover they contained worrying sexual messages.

The letters included a hand drawn picture of male genitalia and vulgar comments, including “You can’t draw a better d**k, pu**y” and “I did this for free food”.

One of the letters Ashleigh Thia and her roommates received in offical Monash envelopes. PHOTO: Ashleigh Thia, Facebook

Ms Thia said she was frightened by the messages and instantly felt unsafe, fearing she was being watched.

“The letters were sealed, we thought they were from Monash. We weren’t expecting these kind of letters,” Ms Thia said.

One of the letters contained a vulgar drawing. PHOTO: Ashleigh Thia, Facebook

The letters were found to have originated from an orientation week welcome activity for new students. Students were encouraged to write a letter to their future selves, and staff posted them at the end of semester one.

The letter Ms Thia opened had her address on it, but no name. She has lived in the rental property since February and it is unclear how her address came to be on the envelope.

She later photographed and posted the letters on Monash StalkerSpace to warn other students.

The anonymous letters had students feeling so unsafe, they considered calling police to investigate. PHOTO: Ashleigh Thia, Facebook

Monash staff member Judith Little responded to her post to let students know where the letters had originated.

“Some students just wrote (what we thought) was their address on the envelopes and we sent them to the address, not knowing the contents and thinking it was going to the authors,” Ms Little wrote.

A Monash University spokesperson said the Safer Communities team was able to confirm the letters were written during O-Week.

The university has now changed the format of the letter writing activity to prevent distressing or offensive letters again being sent out.